Near-Infrared Observations of the Extremely Red Object CL 0939+4713B: An Old Galaxy at Z~1.58?

November 1999 • 1999AJ....118.2065S

Authors • Soifer, B. T. • Matthews, K. • Neugebauer, G. • Armus, L. • Cohen, J. G. • Persson, S. E. • Smail, I.

Abstract • Near-infrared imaging and spectroscopic observations of the extremely red object Cl 0939+4713B (R-K~7 mag) have been obtained with the Near Infrared Camera on the Keck I Telescope of the W. M. Keck Observatory. The imaging shows a slightly elongated structure, while the spectroscopy shows a continuum break that allows us to determine a redshift of z=1.58^+0.01_-0.03 for this system. The fits of a range of models to the infrared spectrum suggest that it is predominantly an old (>10⁹ yr) stellar system that suffers little extinction, while the measured R and I magnitudes suggest an age of ~3x10⁸ yr. The limit on the equivalent width of any emission line in the infrared spectrum suggests that Cl 0939+4713B is not an actively star-forming galaxy. This system, though similar in R-K color to the object HR 10 (also known as J1645+46), is much different in morphology and emission-line strengths, demonstrating the heterogeneity of extremely red extragalactic objects selected on the basis of large R-K values.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=1999AJ....118.2065S
• PDF https://stacks.iop.org/1538-3881/118/2065/pdf
• NED https://ned.ipac.caltech.edu/uri/NED::InRefcode/1999AJ....118.2065S
• PREPRINT http://arxiv.org/abs/astro-ph/9906464
• ELECTR https://doi.org/10.1086%2F301071
• SPIRES http://inspirehep.net/search?p=find+eprint+astro-ph/9906464